Method of adjusting an electromagnetic circuit breaker



Original Filed July 13, 1964 Sheet July 1, 1969 R. SALOMON I 3,452,428

METHOD OF ADJUSTING AN ELECTROMAGNETIC CIRCUIT BREAKER FIG. 2

INVENT OR ROGER SALOMON BY aa j ATTORNEY July 1, 1969 R. SALOMON Sheet 2 of? Original Filed July 13, 1964 INVENTOR ATTORNEYS United States Patent US. Cl. 29-593 7 Claims ABSTRACT OF THE DISCLOSURE In a two-stage voltage regulator the method of individually and independently adjusting the first and second stage voltages by first establishing a predetermined pressure of the leaf spring to urge the armature into engagement with the first stage contact and thereafter altering the flexibility or spring constant of the leaf spring to establish the second stage voltage without affecting the contact pressure responsible for determining the first stage voltage.

This application is a division of my copending application Ser. No. 381,971 filed July -13, 1964- and now Patent No. 3,265,824.

The present invention relates to circuit breakers such as those used in voltage and current regulators of generators, or in make and break switches connecting a generator to a battery.

When electromagnetic circuit breakers are of the type comprising an e-lectromagnet and a movable contact element the latter must offer a certain resistance to the pulling force of the electromagnet.

Said resistance can be applied in different ways as for instance by having a coil spring biasing the movable contact element or a spring leaf urging the armature in a direction opposite the action of the electromagnet. In this second instance a known regulator has the free end of the leaf spring cooperate with a cam mounted on the breaker armature, the rotation of the cam allowing the adjustment of the electromagnetic force exercised on the spring to a desired value. The voltage regulation results from the action of the mechanical resistance of the spring opposing the pulling force of the electromagnet.

In a two stage voltage regulator, two major adjustments occur, namely the voltage adjustment within each stage and the adjustment of passage from one stage to the other. The term stage passage as used herein is defined as the voltage of the regulator sufficient to move the armature from the first stage contact to the second stage contact. As far as the adjustment of passage from one stage to the other is concerned it is necessary to modify either the air gap or the spring flexibility while keeping the initial tension of the spring necessary for the voltage regulation.

When using a coil spring connected to the armature at one end and to the movable contact element at the other end the voltage adjustment can be performed in production by tightening the spring and the stage passage adjustment can be obtained by substituting a spring of different flexibility for the one originally mounted on the device.

When a leaf spring is used it is diificult to obtain the necessary adjustments because said spring has one embedded end and is therefore hardly interchangeable.

The primary object of the invention is to remedy this disadvantage and provide an improved method for adjustment of passage between stages without need for use of interchangeable leaf spring.

The invention specifically concerns an electromagnetic circuit breaker of the type including an electromagnet, a movable armature carrying a contact element, and a leaf spring attached to the armature having a fixed end and the other end cooperating with a stop so as to elastically urge the movable armature and contact element in a direction opposite the action of the electromagnet, said circuit breaker further comprising means for varying the flexibility of the leaf spring by altering its effective length which permits in mass production, and more specifically in the instance of a two-stage regulator, a ready adjustment of the stage passage by varying the characteristic displacement force of the leaf spring.

The known methods for manufacturing and adjusting a conventional regulator in production include mechanically adjusting the regulator first in such manner that the contacts of the first stage open up when the air gap is nominal. Then the spring is tensioned by deforming a part so that the regulator will operate in the first stage at a voltage close to the prescribed voltage. The value of stage passage is noted. To adjust said stage passage the nominal air gap is modified, either by displacing the fixed contact supports or by mechanically deforming the magnetic circuit. This adjustment is only an approximation and presents the disadvantage of modifying the first stage voltage. It is therefore necessary to change the spring tension which again effects the stage passage. These operations may have to be performed many times. This adjusting by successive approximations has the further disadvantage of producing regulators having different air gaps and, consequently, different contact pressure values and different thermal compensation values.

The purpose of the adjusting method according to the present invention is to do away with the disadvantages cited above and to appreciably simplify the adjustment of two-stage regulators while preserving the stability of adjustment by adjusting without parts deformation.

To achieve this, the voltage is first adjusted by tensioning the spring blade by means of a first, or a' temporary, cam the contour of which is located at a variable distance from the center of said cam so as to practically allow a pin-point adjustment of the voltage. The adjustment of the first stage having been performed the stage passage is noted. The value of said passage permits determination of the modification of spring slope necessary to obtain the desired stage passage.

The first, or temporary, cam is replaced by a second, or permanent, cam the contour of which determines the range of contact points when the spring blade is moved, either in the direction of the coil core or away from it, a distance corresponding to the desired slope modification. The device is adjusted with this cam and the stage passage becomes automatically correct.

The adjustment is performed without successive approximations, the value of stage passage is adjusted with an accuracy which only depends upon the chosen difference between two successive cams.

With a set of cams it is therefore possible to vary the spring characteristics in a non-continuous manner so as to adapt its slope to the shape of the equipotential of the regulator.

Thus, all the devices coming out of the assembly line present the same air-gap.

The described adjusting method allows an appreciable decrease of the necessary adjustment tolerances.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein like reference characters indicate like parts throughout the several figures and in which:

FIG. 1 is an end elevation of an electromagnetic circuit breaker provided With means according to the invention wherein the variation of flexibility of the leaf spring is obtained by modifying its effective length;

FIG. 2 is a side elevation, partly in section of the circuit breaker;

FIG. '3 is a plan view of another embodiment of the invention wherein a variation of flexibility of the leaf spring is obtained by changing its effective section;

FIG. 4 is a schematic, side elevational representation of a possible embodiment of the invention wherein only one cam is used divided inseveral segments located in different planes;

FIG. 5 is a schematic, plan view of the cam utilized in the embodiment of FIG. 4;

FIGS. 6 and 7 are schematic views similar to FIG. 4 of other possible realizations of the invention for changing the point of application of the leaf spring on its stop and the restraining force of said spring.

The circuit breaker shown in FIGS. 1 and 2 comprises a frame 1 on which is secured a vertical iron core 2 which supports the excitation winding 3. A movable armature 4 is hingedly secured to frame 1 by a leaf spring 5 aflixed to both. The connection of armature 4 with frame 1 can be realized by means of a separate and distinct leaf spring 6 as shown in FIGS. 1 and 2, or by an extension of the leaf spring 5.

In a known manner, the armature 4 carries a contact 7 cooperating with a fixed contact 8 secured to frame 1.

In a preferred embodiment of the invention the voltage adjustment for opening the breaker is provided by having the free end of leaf spring 5 rest on the cam edge 9 of a cam 9 rotatably mounted on the front portion of frame 1. A toother sector 9 enables said cam 9 to be rotated to lift the free end of the spring to various heights for accurate adjustment of the restraining force of the spring.

According to the invention, in order to provide in mass production an adjustment of the stage passage in addition to the voltage regulation in a two-stage circuit breaker, it is necessary to vary the flexibility of leaf spring 5, that is the location lengthwise of the spring of the point of spring contact on the stop means constituted by cam 9.

A first method of varying the flexibility of the spring 5 is to modify its effective length. One possibility for accomplishing this is to make cam 9 interchangeable. For this purpose, the cam may be removably secured to frame 1 by a screw 10 permanently attached to said frame by welding or any other means and a nut 11. This permits change of the position of the cam contact with leaf spring 5 by choosing an appropriate cam.

It should be noted that the profiles of the diiferent usable cams may be identical, or different, to allow a greater sensitiveness of voltage regulation, but the spring engaging cam edges of these cams must be positioned differently lengthwise of the spring.

As an example, there has been shown in FIG. 2, three cams (two in broken lines) which could be used for varying the flexibility of leaf spring 5 by changing the effective length of said spring. It will be noted that, depending upon which one of the three cams 9, 12 and 13 is used, the point of contact of leaf spring 5 with the differently oriented cam edges 9 12 13 will be displaced from A to B or C.

In the ambodiment of FIGS. 4 and 5, instead of replacing one cam by another to obtain the desired adjustment only one cam 9 is used which is divided in several factors a, b and 0 each located in a different plane lengthwise of the spring 5.

According to another method of realizing the invention for adjusting the stage passage in a two-stage voltage regulator, it is possible to vary the flexibility of the leaf spring by changing its effective section as illustrated in FIG. 3. Leaf spring 5 is trapezoidal in shape, or rectangular if desired, but of decreasing thickness, or still better, characterized by a combination of a given profile and thickness, and instead of being permanently affixed to armature 1 is susceptible to assuming different positions relatively to cam 9. For this purpose, spring 5 is provided in the securing area with slots 14 which cooperate with guides such as clamping screws 15 fastened into threaded openings in armature 4. A number of possible positions of leaf spring 5 relative to cam 9 are obtained by loosenin g and retightening the screws.

-In the embodiment of FIG. 6, an adjustable stop means 16 is substituted for the cam 9 and is secured to armature 1 by means of adjusting screw 17. In this specific instance stop means 16 comprises a U-shaped strip bolted by means of screw 17 which passes through the two branches 16 and 16 in such a manner that the adjustment of said screw 17 will displace branch 16 in the direction xy thereby Varying the location of the contact point of spring 5. Said spring 5 rests upon the head of a screw 18 secured into an extension 16 of branch 16 said screw 18 permitting variation of the restraining force on leaf spring 5 in the direction xy' for adjusting the cut-off voltage.

In the embodiment illustrated in FIG. 7, stop means 19, also secured to armature 1 by suitable means not shown, consists of a leaf having a bent portion 19 onto which the end of leaf spring 5 rests. Said leaf 19 and/or portion 19 can be subjected to different deformations by any appropriate means in both directions xy and x'y'.

In the embodiments of FIGS. 6 and 7, the deformation in the direction xy results in the displacement of the point of contact of leaf spring 5 which provides the adjustment between stages, and the deformation in the direction x'y results in the variation of the restraining force for adjusting the voltage.

With each of the embodiments described above except that of FIG. 3 it will be noted that the improved method of adjustment involves merely tensioning the spring leaf 5 by lifting its free end by cam 9, cam a, part 18 or 19, to provide a desired first stage voltage of operation. The stage passage is then noted and the modification of the slope of spring 5 necessary to obtain the desired stage passage is noted. A second cam 12b, or parts 16 or 19 are then utilized to change the point of contact lengthwise of the spring and by adjustment to yield the required slope of spring 5 to obtain the desired stage passage. Thus the flexibility of the leaf spring is varied by varying its effective length. In the FIG. 3 embodiment the tapered leaf spring 5, is moved longitudinally to obtain the same effect doing away with the need to provide a second cam.

Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

What is claimed is:

1. A method of adjusting an electromagnetic circuit breaker of the type having two stages of operation and including an electromagnet, an armature carrying a contact movable between two fixed contacts and a spring blade having one end cooperating with a stop means to elastically urge the armature in a direction opposite the action of the electromagnet and into engagement with one of the fixed contacts, comprising the steps of tensioning the spring blade by adjusting said stop means to establish a predetermined contact pressure between said armature and said one fixed contact whereby the operating voltage of the first stage of operation is established, measuring the force required to move said armature into engagement with the other of said fixed contacts to thereby determine the modified flexibility of said spring blade necessary to obtain the second passage, and then modifying the flexibility of the spring blade by longitudinally shifting the point of contact of the spring blade with said adjustable stop means to obtain said modified flexibility thereof and thereby establish a predetermined voltage increase necessary to move the armature into engagement with the other contact and maintain said predetermined contact pressure between said armature and one fixed contact.

2. A method of adjusting an electromagnetic circuit breaker of the type having at least two stages of operation and including an electromagnet, an armature carrying a contact movable between two fixed contacts and a spring blade carrying the armature and having its two ends contacting a frame and an adjustable stop means respectively to elastically urge the armature away from the electromagnet and into engagement with one fixed contact, comprising the steps of tensioning the spring blade for a desired first stage operation by adjusting said stop means to establish a predetermined contact pressure between the armature and fixed contact, measuring the stage passage by measuring the voltage increase necessary to move the armature into engagement with the other fixed contact and thereby to determined a modified flexibility of the spring blade necessary to obtain a desired second stage passage, and longitudinally shifting the point of contact of the spring blade with said adjustable stop means to establish a stage passage within predetermined limits and maintain said predetermined contact pressure between said armature and the one fixed contact.

3. A method of adjusting an electromagnetic circuit breaker according to claim 2 wherein said shifting of the point of contact of the spring blade is performed by uti1izing a tapered spring and moving the spring longitudinally with respect to said frame and stop means.

4. A method of adjusting an electromagnetic circuit breaker according to claim 2 wherein said shifting of the point of contact of the spring blade is accomplished by bending a portion of said adjustable stop means longitudinally of the spring.

5. A method of adjusting an electromagnetic circuit breaker according to claim 2 wherein said tensioning of the spring blade for a desired first stage operation is performed by moving a temporary cam forming part of said adjustable stop means, and said shifting of the point of contact of the spring blade is obtained by substituting for said temporary cam a permanent cam disposed in a plane displaced longitudinally of the spring blade with respect to the plane of the temporary cam.

6. A method of adjusting an electromagnetic circuit breaker according to claim 2 wherein said tensioning of the spring blade for a desired first stage operation is performed by a first cam segment and said shifting of the point of contact of the spring blade is accomplished by utilizing a second cam segment, both said cam segments forming part of said adjustable stop means and being disposed in diiferent planes displaced longitudinally of the spring blade.

7. A method of adjusting an electromagnetic circuit breaker according to claim 2 wherein said tensioning of the spring blade for a desired first stage operation is performed by moving a part of said adjustable stop means in a plane perpendicular to the spring blade, and said shifting of the point of contact of the spring blade is accomplished by bending a part of the adjustable stop means longitudinally of the spring blade.

References Cited UNITED STATES PATENTS 315,568 4/1915 Stitzel et a1 335-273 1,693,491 11/1928 Ogden 33596 2,526,455 10/1950 Bonanno 335-273 2,585,684 2/ 1952 Roggenstein 335274 2,911,497 11/1959 Prickett 335274 2,914,713 11/1959 Rice 335-274 3,201,659 '8/ 1965 Poulton et al. 335273 JOHN F. CAMPBELL, Primary Examiner. R. W. CHURCH, Assistant Examiner.

US. Cl. X.R. 29407, 622; 335194, 197 

